Proceedings of International Congress on Bioactive Compounds and International Workshop on Bioactive Compounds
Proceedings of 2nd International Congress on Bioactive Compounds

Xylitol is a bioactive compound from the family of polyols derived from lignocellulosic raw material. It has many applications in the food and dental industry mainly due to its properties it means sweetening power similar to sucrose, but with a considerably lower caloric content and anticariogenic action, mainly against caries. Currently, it is industrially produced by chemical means, but it has a high operating cost and is not environmentally friendly. An alternative to this process is the biotechnological route, as it requires milder operating conditions and a reduction in toxic residues. However, the viability of this process depends on the downstream stage, which is not consolidated and makes the process more expensive. Thus, this work aims to obtain xylitol crystals contained in a fermented broth of hemicellulose hydrolysate from sugarcane bagasse through purification steps and the chemical characterization of the crystals obtained. For the purification step, adsorption methodologies were carried out in fixed bed columns and crystallization. The adsorption conditions were step feeding with ascending flow, temperature of 70 ºC, activated carbon as adsorbent, rate of 3.5 mL/min and 1.5 cm/min surface speed. The adsorption proved to be efficient in the clarification of the fermented broth, separating colored compounds at 420 nm and 560 nm, proteins and ethanol, main contaminants of fermented broth, with retention coefficient (RC) of 98.64 %, 98.50 %, 97.94 % and 99.34 %, respectively. The purification factor (PF) of xylitol in relation to ethanol was 53.87 and in relation to protein was 17.35. The crystallization method was by cooling to 5 °C for 24 hours, with isopropanol as antisolvent and secondary nucleation, with the addition of standard xylitol crystals. For the characterization of the crystals, three samples were analyzed, which were the standard xylitol, the standard xylitol crystallized by the crystallization methodology and the crystallized xylitol obtained from the hemicellulose hydrolysate of sugarcane bagasse. The characterization of purified crystals was performed using Scanning Electron Microscopy (SEM) techniques, which showed that xylitol crystals have a more rounded morphology and geometry than standard xylitol; by Fourier Transform Infrared Spectroscopy (FTIR), where it was possible to observe the absorption bands referring to the hydroxyl groups, between 3500 cm−1 to 3000 cm−1 and 1470 cm−1 to 750 cm−1, present in the chemical structure of xylitol. And other absorption bands that are not characteristic of this bioactive compound. It was also characterized by X-ray Diffraction (XRD), where crystalline phases referring to xylitol and similar crystallinities between the analytes were found. Therefore, the purification results are promising for the viability of this biotechnological route to obtain xylitol.